The general objective is to determine the feasibility of attaching antitumor antibodies to liposomes and to assess the ability to confer specificity of cell interaction to liposomes. Affinity-purified goat antibodies against carcinoembryonic antigen of the human digestive tract (CEA) will be coupled to fatty acids, gangliosides, or phospholipids and inserted onto the surface of small and large unilamellar vesicles. Using liposomes coated with antibody or normal immunoglobulin in a paired-label technique, the tissue distribution and homing characteristics of liposome-antibody complexes are determined in a CEA-producing, human tumor-hamster host model. The influence of immunoliposome size, antibody activity, chemical composition, and route of injection on the efficacy of tumor localization will be assessed by tissue counting and photoscanning techniques. Further studies will evaluate the ability of immunoliposomes to deliver therapeutic effective doses of cytotoxic drugs, methotrexate and 5-fluorouracil, to the tumor. The ultimate goal of this research is to devise liposomes with appropriate homing capabilities that can selectively transport antitumor drugs, immunostimulators, and imaging agents to malignant cells in vivo, thereby increasing therapeutic and diagnostic efficacy.